1. Field of the Invention
The present invention relates generally to apparatus and methods for reducing the size of material, and, more particularly, to apparatus and methods for providing granulated materials.
2. Description of the Prior Art
Machines that reduce large pieces or clumps of material into smaller pieces are well known in the art. Generally, such machines employ a grinder element that is rotated by a motor. There are certain disadvantages, however, associated with the use of such machines. One problem is the tendency of the ground up material to escape the grinding chamber and become trapped between the shaft which rotates the grinder and the grinding chamber. Although many types of special seals have been developed over the years to seal drive shafts from a driven grinding element, such seals often fail or need periodic maintenance to retain their integrity. In this respect, it would be desirable if a device for granulating material were provided which does not permit ground material to become trapped between a shaft which rotates a grinding element and a grinding chamber. Also, it would be desirable if a device were provided for granulating material that does not need a seal between a grinding element and a drive shaft.
Another problem associated with devices that have rotating grinding elements is vibration that can occur when the grinding element rotates in the process of granulating material. In this respect, it would be desirable if a grinding device were provided which did not undergo vibrations caused by a rotating grinding element.
When material is comminuted into smaller pieces, heat is often generated during the comminution process. Excessive heat build up can often damage both the material being ground and the apparatus in which the grinding is carried out. In this respect, it would be desirable if a grinding device were provided which carried heat away from the material being ground.
When a material is being ground, the dust particles are often formed. In this respect, it would be desirable if a grinding device were provided which collected the dust produced during the grinding process.
During a grinding process, particles of selected size are often desired. Particles which are within the desired size range are collected. Particles that are larger than the desired size can be recycled to be ground again. In this respect, it would be desirable if a grinding device were provided which included means for collecting particles in the desired size range and included means for recycling particles larger than desired.
During a grinding operation, control of ground particles is often related to the time period that the material undergoes the grinding operation. In this respect, it would be desirable if a grinding device were provided which permitted control of the time period in which the material undergoes the grinding operation.
In a complex process for grinding, collecting, and recycling a material, the material must be moved from one station to another. Conveyor belts may be used, but particulate material ;may be blown off the conveyor. In this respect, it would be desirable if a grinding device were provided that included means for conveying material from one station to another without losing material.
Conveyor belts are complex devices that include many moving parts. In conveying materials from one station to another it would be desirable if conveying means were provided which were simple and did not include moving parts.
Grinding processes which include a rotating element in a grinding chamber are often batch processes. For a number of reasons, continuous processes are often preferred over batch processes. In this respect, it would be desirable if a grinding device were provided that permitted the grinding process to be carried out continuously.
Thus, while the foregoing body of prior art indicates it to be well known to use devices to grind and granulate material, the prior art described above does not teach or suggest a media granulation apparatus which has the following combination of desirable features: (1) does not permit ground material to become trapped between a drive shaft, which rotates a grinding element, and a grinding chamber; (2) does not need a seal between a grinding element and a drive shaft; (3) does not undergo vibrations caused by a rotating grinding element; (4) carries heat away from the material being ground; (5) collects the dust produced during the grinding process; (6) includes means for collecting particles in the desired size range and includes means for recycling particles larger than desired; (7) permits control of the time period in which the material undergoes the grinding operation; (8) includes means for conveying material from one station to another without losing material; (9) permits the grinding process to be carried out continuously; and (10) provides conveying means which are simple and do not include moving parts. The foregoing desired characteristics are provided by the unique media granulation apparatus of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.